Sample adaptive offset (sao) in accordance with video coding

ABSTRACT

Sample adaptive offset (SAO) in accordance with video coding. SAO filtering may be performed before de-blocking processing (e.g., in accordance with video signal decoding and/or encoding). For example, a receiver and/or decoder communication device may receive signaling from a transmitter and/or encoder communication device that includes various band offsets. Corresponding band indices may be determined via analysis of the received video signal (e.g., received from the transmitter and/or encoder communication device), inferentially without requiring signaling of such band indices from the transmitter and/or encoder communication device. Upon appropriate analysis of one or more largest coding units (LCUs) generated from the video signal to determine a pixel value distribution (e.g., which may be using a histogram in one instance), then based on that pixel value distribution, the band indices are identified and the band offsets applied thereto.

CROSS REFERENCE TO RELATED PATENTS/PATENT APPLICATIONS

The present U.S. Utility Patent Application claims priority pursuant to35 U.S.C. § 120 as a continuation of U.S. Utility application Ser. No.16/687,395, entitled “Sample adaptive offset (SAO) in accordance withvideo coding,” filed Nov. 18, 2019, issuing as U.S. Pat. No. 11,166,011on Nov. 2, 2021; which claims priority pursuant to 35 U.S.C. § 120 as acontinuation of U.S. Utility application Ser. No. 15/053,304, entitled“Sample adaptive offset (SAO) in accordance with video coding,” filedFeb. 25, 2016, issuing as U.S. Pat. No. 10,484,677 on Nov. 19, 2019;which claims priority pursuant to 35 U.S.C. § 120 as a continuation ofU.S. Utility application Ser. No. 13/758,169, entitled “Sample adaptiveoffset (SAO) in accordance with video coding,” filed Feb. 4, 2013,issued as U.S. Pat. No. 9,282,328 on Mar. 8, 2016; which claims prioritypursuant to 35 U.S.C. § 119(e) to U.S. Provisional Application No.61/597,683, entitled “Frequency domain sample adaptive offset,” filedFeb. 10, 2012, U.S. Provisional Application No. 61/598,326, entitled“Sample adaptive offset (SAO) in accordance with video coding,” filedFeb. 13, 2012, and U.S. Provisional Application No. 61/603,190, entitled“Frequency domain sample adaptive offset (SAO),” filed Feb. 24, 2012,all of which are hereby incorporated herein by reference in theirentirety and made part of the present U.S. Utility Patent Applicationfor all purposes.

INCORPORATION BY REFERENCE

The following U.S. Utility Patent Application is hereby incorporatedherein by reference in its entirety and made part of the present U.S.Utility Patent Application for all purposes:

1. U.S. Utility patent application Ser. No. 13/623,765, entitled“Frequency domain sample adaptive offset (SAO),” filed Sep. 20, 2012,pending, which claims priority pursuant to 35 U.S.C. § 119(e) to thefollowing U.S. Provisional Patent Application which is herebyincorporated herein by reference in its entirety and made part of thepresent U.S. Utility Patent Application for all purposes:

-   -   1.1. U.S. Provisional Application No. 61/597,683, entitled        “Frequency domain sample adaptive offset,” filed Feb. 10, 2012.    -   1.2. U.S. Provisional Application No. 61/603,190, entitled        “Frequency domain sample adaptive offset (SAO),” filed Feb. 24,        2012.

The following standards/draft standards are hereby incorporated hereinby reference in their entirety and are made part of the present U.S.Utility Patent Application for all purposes:

1. “High Efficiency Video Coding (HEVC) text specification draft 10 (forFDIS & Consent),” Joint Collaborative Team on Video Coding (JCT-VC) ofITU-T SG 16 WP 3 and ISO/IEC JTC 1/SC 29/WG 11, 12th Meeting: Geneva,CH, 14-23 Jan. 2013, Document: JCTVC-L1003_v11, 332 pages.

2. International Telecommunication Union, ITU-T, TELECOMMUNICATIONSTANDARDIZATION SECTOR OF ITU, H.264 (03/2010), SERIES H: AUDIOVISUALAND MULTIMEDIA SYSTEMS, Infrastructure of audiovisual services—Coding ofmoving video, Advanced video coding for generic audiovisual services,Recommendation ITU-T H.264, also alternatively referred to asInternational Telecomm ISO/IEC 14496-10—MPEG-4 Part 10, AVC (AdvancedVideo Coding), H.264/MPEG-4 Part 10 or AVC (Advanced Video Coding), ITUH.264/MPEG4-AVC, or equivalent.

BACKGROUND OF THE INVENTION Technical Field of the Invention

The invention relates generally to digital video processing; and, moreparticularly, it relates to processing and operations in accordance withsuch digital video processing.

Description of Related Art

Communication systems that operate to communicate digital media (e.g.,images, video, data, etc.) have been under continual development formany years. With respect to such communication systems employing someform of video data, a number of digital images are output or displayedat some frame rate (e.g., frames per second) to effectuate a videosignal suitable for output and consumption. Within many suchcommunication systems operating using video data, there can be atrade-off between throughput (e.g., number of image frames that may betransmitted from a first location to a second location) and video and/orimage quality of the signal eventually to be output or displayed. Thepresent art does not adequately or acceptably provide a means by whichvideo data may be transmitted from a first location to a second locationin accordance with providing an adequate or acceptable video and/orimage quality, ensuring a relatively low amount of overhead associatedwith the communications, relatively low complexity of the communicationdevices at respective ends of communication links, etc.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 and FIG. 2 illustrate various embodiments of communicationsystems.

FIG. 3A illustrates an embodiment of a computer.

FIG. 3B illustrates an embodiment of a laptop computer.

FIG. 3C illustrates an embodiment of a high definition (HD) television.

FIG. 3D illustrates an embodiment of a standard definition (SD)television.

FIG. 3E illustrates an embodiment of a handheld media unit.

FIG. 3F illustrates an embodiment of a set top box (STB).

FIG. 3G illustrates an embodiment of a digital video disc (DVD) player.

FIG. 3H illustrates an embodiment of a generic digital image and/orvideo processing device.

FIG. 4, FIG. 5, and FIG. 6 are diagrams illustrating various embodimentsof video encoding architectures.

FIG. 7 is a diagram illustrating an embodiment of intra-predictionprocessing.

FIG. 8 is a diagram illustrating an embodiment of inter-predictionprocessing.

FIG. 9 and FIG. 10 are diagrams illustrating various embodiments ofvideo decoding architectures.

FIG. 11 illustrates an embodiment of a band offset sample adaptiveoffset (SAO) filtering process.

FIG. 12 illustrates an alternative embodiment of a video encodingarchitecture.

FIG. 13 illustrates various embodiments of indication (adaptive and/orexplicit signaling) transmitted band offsets in sample adaptive offset(SAO) band offset mode.

FIG. 14 illustrates various embodiments of indication (adaptive and/orexplicit signaling) band granularity in SAO band offset mode.

FIG. 15 illustrates an embodiment of implicit band index signaling.

FIG. 16 illustrates an alternative embodiment of implicit band indexsignaling.

FIG. 17 illustrates an embodiment of band offset coding.

FIG. 18 and FIG. 19 illustrate various embodiments of method foroperating one or more devices (e.g., communication devices, receiverand/or decoder devices, transmitter and/or encoder devices, etc.).

DETAILED DESCRIPTION OF THE INVENTION

Within many devices that use digital media such as digital video,respective images thereof, being digital in nature, are representedusing pixels. Within certain communication systems, digital media can betransmitted from a first location to a second location at which suchmedia can be output or displayed. The goal of digital communicationssystems, including those that operate to communicate digital video, isto transmit digital data from one location, or subsystem, to anothereither error free or with an acceptably low error rate. As shown in FIG.1, data may be transmitted over a variety of communications channels ina wide variety of communication systems: magnetic media, wired,wireless, fiber, copper, and/or other types of media as well.

FIG. 1 and FIG. 2 are diagrams illustrate various embodiments ofcommunication systems, 100 and 200, respectively.

Referring to FIG. 1, this embodiment of a communication system 100 is acommunication channel 199 that communicatively couples a communicationdevice 110 (including a transmitter 112 having an encoder 114 andincluding a receiver 116 having a decoder 118) situated at one end ofthe communication channel 199 to another communication device 120(including a transmitter 126 having an encoder 128 and including areceiver 122 having a decoder 124) at the other end of the communicationchannel 199. In some embodiments, either of the communication devices110 and 120 may only include a transmitter or a receiver. There areseveral different types of media by which the communication channel 199may be implemented (e.g., a satellite communication channel 130 usingsatellite dishes 132 and 134, a wireless communication channel 140 usingtowers 142 and 144 and/or local antennae 152 and 154, a wiredcommunication channel 150, and/or a fiber-optic communication channel160 using electrical to optical (E/O) interface 162 and optical toelectrical (O/E) interface 164)). In addition, more than one type ofmedia may be implemented/interfaced together thereby forming thecommunication channel 199.

It is noted that such communication devices 110 and/or 120 may bestationary or mobile without departing from the scope and spirit of theinvention. For example, either one or both of the communication devices110 and 120 may be implemented in a fixed location or may be a mobilecommunication device with capability to associate with and/orcommunicate with more than one network access point (e.g., differentrespective access points (APs) in the context of a mobile communicationsystem including one or more wireless local area networks (WLANs),different respective satellites in the context of a mobile communicationsystem including one or more satellite, or generally, differentrespective network access points in the context of a mobilecommunication system including one or more network access points bywhich communications may be effectuated with communication devices 110and/or 120.

To reduce transmission errors that may undesirably be incurred within acommunication system, error correction and channel coding schemes areoften employed. Generally, these error correction and channel codingschemes involve the use of an encoder at the transmitter end of thecommunication channel 199 and a decoder at the receiver end of thecommunication channel 199.

Any of various types of ECC codes described can be employed within anysuch desired communication system (e.g., including those variationsdescribed with respect to FIG. 1), any information storage device (e.g.,hard disk drives (HDDs), network information storage devices and/orservers, etc.) or any application in which information encoding and/ordecoding is desired.

Generally speaking, when considering a communication system in whichvideo data is communicated from one location, or subsystem, to another,video data encoding may generally be viewed as being performed at atransmitting end of the communication channel 199, and video datadecoding may generally be viewed as being performed at a receiving endof the communication channel 199.

Also, while the embodiment of this diagram shows bi-directionalcommunication being capable between the communication devices 110 and120, it is of course noted that, in some embodiments, the communicationdevice 110 may include only video data encoding capability, and thecommunication device 120 may include only video data decodingcapability, or vice versa (e.g., in a uni-directional embodiment such asin accordance with a video broadcast embodiment).

Referring to the communication system 200 of FIG. 2, at a transmittingend of a communication channel 299, information bits 201 (e.g.,corresponding particularly to video data in one embodiment) are providedto a transmitter 297 that is operable to perform encoding of theseinformation bits 201 using an encoder and symbol mapper 220 (which maybe viewed as being distinct functional blocks 222 and 224, respectively,such that encoded information bits 202 are output from encoder 222 andprovided to symbol mapper 224) thereby generating a sequence ofdiscrete-valued modulation symbols 203 that is provided to a transmitdriver 230 that uses a DAC (Digital to Analog Converter) 232 to generatea continuous-time transmit signal 204 and a transmit filter 234 togenerate a filtered, continuous-time transmit signal 205 thatsubstantially comports with the communication channel 299. At areceiving end of the communication channel 299, continuous-time receivesignal 206 is provided to an AFE (Analog Front End) 260 that includes areceive filter 262 (that generates a filtered, continuous-time receivesignal 207) and an ADC (Analog to Digital Converter) 264 (that generatesdiscrete-time receive signals 208). A metric generator 270 calculatesmetrics 209 (e.g., on either a symbol and/or bit basis) that areemployed by a decoder 280 to make best estimates of the discrete-valuedmodulation symbols and information bits encoded therein 210.

Within each of the transmitter 297 and the receiver 298, any desiredintegration of various components, blocks, functional blocks,circuitries, etc. Therein may be implemented. For example, this diagramshows a processing module 280 a as including the encoder and symbolmapper 220 and all associated, corresponding components therein, and aprocessing module 280 is shown as including the metric generator 270 andthe decoder 280 and all associated, corresponding components therein.Such processing modules 280 a and 280 b may be respective integratedcircuits. Of course, other boundaries and groupings may alternatively beperformed without departing from the scope and spirit of the invention.For example, all components within the transmitter 297 may be includedwithin a first processing module or integrated circuit, and allcomponents within the receiver 298 may be included within a secondprocessing module or integrated circuit. Alternatively, any othercombination of components within each of the transmitter 297 and thereceiver 298 may be made in other embodiments.

As with the previous embodiment, such a communication system 200 may beemployed for the communication of video data is communicated from onelocation, or subsystem, to another (e.g., from transmitter 297 to thereceiver 298 via the communication channel 299).

Digital image and/or video processing of digital images and/or media(including the respective images within a digital video signal) may beperformed by any of the various devices depicted below in FIG. 3A-3H toallow a user to view such digital images and/or video. These variousdevices do not include an exhaustive list of devices in which the imageand/or video processing described herein may be effectuated, and it isnoted that any generic digital image and/or video processing device maybe implemented to perform the processing described herein withoutdeparting from the scope and spirit of the invention.

FIG. 3A illustrates an embodiment of a computer 301. The computer 301can be a desktop computer, or an enterprise storage devices such aserver, of a host computer that is attached to a storage array such as aredundant array of independent disks (RAID) array, storage router, edgerouter, storage switch and/or storage director. A user is able to viewstill digital images and/or video (e.g., a sequence of digital images)using the computer 301. Oftentimes, various image and/or video viewingprograms and/or media player programs are included on a computer 301 toallow a user to view such images (including video).

FIG. 3B illustrates an embodiment of a laptop computer 302. Such alaptop computer 302 may be found and used in any of a wide variety ofcontexts. In recent years, with the ever-increasing processingcapability and functionality found within laptop computers, they arebeing employed in many instances where previously higher-end and morecapable desktop computers would be used. As with computer 301, laptopcomputer 302 may include various image viewing programs and/or mediaplayer programs to allow a user to view such images (including video).

FIG. 3C illustrates an embodiment of a high definition (HD) television303. Many HD televisions 303 include an integrated tuner to allow thereceipt, processing, and decoding of media content (e.g., televisionbroadcast signals) thereon. Alternatively, sometimes an HD television303 receives media content from another source such as a digital videodisc (DVD) player, set top box (STB) that receives, processes, anddecodes a cable and/or satellite television broadcast signal. Regardlessof the particular implementation, the HD television 303 may beimplemented to perform image and/or video processing as describedherein. Generally speaking, an HD television 303 has capability todisplay HD media content and oftentimes is implemented having a 16:9widescreen aspect ratio.

FIG. 3D illustrates an embodiment of a standard definition (SD)television 304. Of course, an SD television 304 is somewhat analogous toan HD television 303, with at least one difference being that the SDtelevision 304 does not include capability to display HD media content,and an SD television 304 oftentimes is implemented having a 4:3 fullscreen aspect ratio. Nonetheless, even an SD television 304 may beimplemented to perform image and/or video processing as describedherein.

FIG. 3E illustrates an embodiment of a handheld media unit 305. Ahandheld media unit 305 may operate to provide general storage orstorage of image/video content information such as joint photographicexperts group (JPEG) files, tagged image file format (TIFF), bitmap,motion picture experts group (MPEG) files, Windows Media (WMA/WMV)files, other types of video content such as MPEG4 files, etc. forplayback to a user, and/or any other type of information that may bestored in a digital format. Historically, such handheld media units wereprimarily employed for storage and playback of audio media; however,such a handheld media unit 305 may be employed for storage and playbackof virtual any media (e.g., audio media, video media, photographicmedia, etc.). Moreover, such a handheld media unit 305 may also includeother functionality such as integrated communication circuitry for wiredand wireless communications. Such a handheld media unit 305 may beimplemented to perform image and/or video processing as describedherein.

FIG. 3F illustrates an embodiment of a set top box (STB) 306. Asmentioned above, sometimes a STB 306 may be implemented to receive,process, and decode a cable and/or satellite television broadcast signalto be provided to any appropriate display capable device such as SDtelevision 304 and/or HD television 303. Such an STB 306 may operateindependently or cooperatively with such a display capable device toperform image and/or video processing as described herein.

FIG. 3G illustrates an embodiment of a digital video disc (DVD) player307. Such a DVD player may be a Blu-Ray DVD player, an HD capable DVDplayer, an SD capable DVD player, an up-sampling capable DVD player(e.g., from SD to HD, etc.) without departing from the scope and spiritof the invention. The DVD player may provide a signal to any appropriatedisplay capable device such as SD television 304 and/or HD television303. The DVD player 305 may be implemented to perform image and/or videoprocessing as described herein.

FIG. 3H illustrates an embodiment of a generic digital image and/orvideo processing device 308. Again, as mentioned above, these variousdevices described above do not include an exhaustive list of devices inwhich the image and/or video processing described herein may beeffectuated, and it is noted that any generic digital image and/or videoprocessing device 308 may be implemented to perform the image and/orvideo processing described herein without departing from the scope andspirit of the invention.

FIG. 4, FIG. 5, and FIG. 6 are diagrams illustrating various embodiments400 and 500, and 600, respectively, of video encoding architectures.

Referring to embodiment 400 of FIG. 4, as may be seen with respect tothis diagram, an input video signal is received by a video encoder. Incertain embodiments, the input video signal is composed of coding units(CUs) or macro-blocks (MBs). The size of such coding units ormacro-blocks may be varied and can include a number of pixels typicallyarranged in a square shape. In one embodiment, such coding units ormacro-blocks have a size of 16×16 pixels. However, it is generally notedthat a macro-block may have any desired size such as N×N pixels, where Nis an integer (e.g., 16×16, 8×8, or 4×4). Of course, someimplementations may include non-square shaped coding units ormacro-blocks, although square shaped coding units or macro-blocks areemployed in a preferred embodiment.

The input video signal may generally be referred to as corresponding toraw frame (or picture) image data. For example, raw frame (or picture)image data may undergo processing to generate luma and chroma samples.In some embodiments, the set of luma samples in a macro-block is of oneparticular arrangement (e.g., 16×16), and set of the chroma samples isof a different particular arrangement (e.g., 8×8). In accordance withthe embodiment depicted herein, a video encoder processes such sampleson a block by block basis.

The input video signal then undergoes mode selection by which the inputvideo signal selectively undergoes intra and/or inter-predictionprocessing. Generally speaking, the input video signal undergoescompression along a compression pathway. When operating with no feedback(e.g., in accordance with neither inter-prediction norintra-prediction), the input video signal is provided via thecompression pathway to undergo transform operations (e.g., in accordancewith discrete cosine transform (DCT)). Of course, other transforms maybe employed in alternative embodiments. In this mode of operation, theinput video signal itself is that which is compressed. The compressionpathway may take advantage of the lack of high frequency sensitivity ofhuman eyes in performing the compression.

However, feedback may be employed along the compression pathway byselectively using inter- or intra-prediction video encoding. Inaccordance with a feedback or predictive mode of operation, thecompression pathway operates on a (relatively low energy) residual(e.g., a difference) resulting from subtraction of a predicted value ofa current macro-block from the current macro-block. Depending upon whichform of prediction is employed in a given instance, a residual ordifference between a current macro-block and a predicted value of thatmacro-block based on at least a portion of that same frame (or picture)or on at least a portion of at least one other frame (or picture) isgenerated.

The resulting modified video signal then undergoes transform operationsalong the compression pathway. In one embodiment, a discrete cosinetransform (DCT) operates on a set of video samples (e.g., luma, chroma,residual, etc.) to compute respective coefficient values for each of apredetermined number of basis patterns. For example, one embodimentincludes 64 basis functions (e.g., such as for an 8×8 sample). Generallyspeaking, different embodiments may employ different numbers of basisfunctions (e.g., different transforms). Any combination of thoserespective basis functions, including appropriate and selectiveweighting thereof, may be used to represent a given set of videosamples. Additional details related to various ways of performingtransform operations are described in the technical literatureassociated with video encoding including those standards/draft standardsthat have been incorporated by reference as indicated above. The outputfrom the transform processing includes such respective coefficientvalues. This output is provided to a quantizer.

Generally, most image blocks will typically yield coefficients (e.g.,DCT coefficients in an embodiment operating in accordance with discretecosine transform (DCT)) such that the most relevant DCT coefficients areof lower frequencies. Because of this and of the human eyes' relativelypoor sensitivity to high frequency visual effects, a quantizer may beoperable to convert most of the less relevant coefficients to a value ofzero. That is to say, those coefficients whose relative contribution isbelow some predetermined value (e.g., some threshold) may be eliminatedin accordance with the quantization process. A quantizer may also beoperable to convert the significant coefficients into values that can becoded more efficiently than those that result from the transformprocess. For example, the quantization process may operate by dividingeach respective coefficient by an integer value and discarding anyremainder. Such a process, when operating on typical coding units ormacro-blocks, typically yields a relatively low number of non-zerocoefficients which are then delivered to an entropy encoder for losslessencoding and for use in accordance with a feedback path which may selectintra-prediction and/or inter-prediction processing in accordance withvideo encoding.

An entropy encoder operates in accordance with a lossless compressionencoding process. In comparison, the quantization operations aregenerally lossy. The entropy encoding process operates on thecoefficients provided from the quantization process. Those coefficientsmay represent various characteristics (e.g., luma, chroma, residual,etc.). Various types of encoding may be employed by an entropy encoder.For example, context-adaptive binary arithmetic coding (CABAC) and/orcontext-adaptive variable-length coding (CAVLC) may be performed by theentropy encoder. For example, in accordance with at least one part of anentropy coding scheme, the data is converted to a (run, level) pairing(e.g., data 14, 3, 0, 4, 0, 0, −3 would be converted to the respective(run, level) pairs of (0, 14), (0, 3), (1, 4), (2, −3)). In advance, atable may be prepared that assigns variable length codes for valuepairs, such that relatively shorter length codes are assigned torelatively common value pairs, and relatively longer length codes areassigned for relatively less common value pairs.

As the reader will understand, the operations of inverse quantizationand inverse transform correspond to those of quantization and transform,respectively. For example, in an embodiment in which a DCT is employedwithin the transform operations, then an inverse DCT (IDCT) is thatemployed within the inverse transform operations.

A picture buffer, alternatively referred to as a digital picture bufferor a DPB, receives the signal from the IDCT module; the picture bufferis operative to store the current frame (or picture) and/or one or moreother frames (or pictures) such as may be used in accordance withintra-prediction and/or inter-prediction operations as may be performedin accordance with video encoding. It is noted that in accordance withintra-prediction, a relatively small amount of storage may besufficient, in that, it may not be necessary to store the current frame(or picture) or any other frame (or picture) within the frame (orpicture) sequence. Such stored information may be employed forperforming motion compensation and/or motion estimation in the case ofperforming inter-prediction in accordance with video encoding.

In one possible embodiment, for motion estimation, a respective set ofluma samples (e.g., 16×16) from a current frame (or picture) arecompared to respective buffered counterparts in other frames (orpictures) within the frame (or picture) sequence (e.g., in accordancewith inter-prediction). In one possible implementation, a closestmatching area is located (e.g., prediction reference) and a vectoroffset (e.g., motion vector) is produced. In a single frame (orpicture), a number of motion vectors may be found and not all willnecessarily point in the same direction. One or more operations asperformed in accordance with motion estimation are operative to generateone or more motion vectors.

Motion compensation is operative to employ one or more motion vectors asmay be generated in accordance with motion estimation. A predictionreference set of samples is identified and delivered for subtractionfrom the original input video signal in an effort hopefully to yield arelatively (e.g., ideally, much) lower energy residual. If suchoperations do not result in a yielded lower energy residual, motioncompensation need not necessarily be performed and the transformoperations may merely operate on the original input video signal insteadof on a residual (e.g., in accordance with an operational mode in whichthe input video signal is provided straight through to the transformoperation, such that neither intra-prediction nor inter-prediction areperformed), or intra-prediction may be utilized and transform operationsperformed on the residual resulting from intra-prediction. Also, if themotion estimation and/or motion compensation operations are successful,the motion vector may also be sent to the entropy encoder along with thecorresponding residual's coefficients for use in undergoing losslessentropy encoding.

The output from the overall video encoding operation is an output bitstream. It is noted that such an output bit stream may of course undergocertain processing in accordance with generating a continuous timesignal which may be transmitted via a communication channel. Forexample, certain embodiments operate within wireless communicationsystems. In such an instance, an output bitstream may undergoappropriate digital to analog conversion, frequency conversion, scaling,filtering, modulation, symbol mapping, and/or any other operationswithin a wireless communication device that operate to generate acontinuous time signal capable of being transmitted via a communicationchannel, etc.

Referring to embodiment 500 of FIG. 5, as may be seen with respect tothis diagram, an input video signal is received by a video encoder. Incertain embodiments, the input video signal is composed of coding unitsor macro-blocks (and/or may be partitioned into coding units (CUs)). Thesize of such coding units or macro-blocks may be varied and can includea number of pixels typically arranged in a square shape. In oneembodiment, such coding units or macro-blocks have a size of 16×16pixels. However, it is generally noted that a macro-block may have anydesired size such as N×N pixels, where N is an integer. Of course, someimplementations may include non-square shaped coding units ormacro-blocks, although square shaped coding units or macro-blocks areemployed in a preferred embodiment.

The input video signal may generally be referred to as corresponding toraw frame (or picture) image data. For example, raw frame (or picture)image data may undergo processing to generate luma and chroma samples.In some embodiments, the set of luma samples in a macro-block is of oneparticular arrangement (e.g., 16×16), and set of the chroma samples isof a different particular arrangement (e.g., 8×8). In accordance withthe embodiment depicted herein, a video encoder processes such sampleson a block by block basis.

The input video signal then undergoes mode selection by which the inputvideo signal selectively undergoes intra and/or inter-predictionprocessing. Generally speaking, the input video signal undergoescompression along a compression pathway. When operating with no feedback(e.g., in accordance with neither inter-prediction norintra-prediction), the input video signal is provided via thecompression pathway to undergo transform operations (e.g., in accordancewith discrete cosine transform (DCT)). Of course, other transforms maybe employed in alternative embodiments. In this mode of operation, theinput video signal itself is that which is compressed. The compressionpathway may take advantage of the lack of high frequency sensitivity ofhuman eyes in performing the compression.

However, feedback may be employed along the compression pathway byselectively using inter- or intra-prediction video encoding. Inaccordance with a feedback or predictive mode of operation, thecompression pathway operates on a (relatively low energy) residual(e.g., a difference) resulting from subtraction of a predicted value ofa current macro-block from the current macro-block. Depending upon whichform of prediction is employed in a given instance, a residual ordifference between a current macro-block and a predicted value of thatmacro-block based on at least a portion of that same frame (or picture)or on at least a portion of at least one other frame (or picture) isgenerated.

The resulting modified video signal then undergoes transform operationsalong the compression pathway. In one embodiment, a discrete cosinetransform (DCT) operates on a set of video samples (e.g., luma, chroma,residual, etc.) to compute respective coefficient values for each of apredetermined number of basis patterns. For example, one embodimentincludes 64 basis functions (e.g., such as for an 8×8 sample). Generallyspeaking, different embodiments may employ different numbers of basisfunctions (e.g., different transforms). Any combination of thoserespective basis functions, including appropriate and selectiveweighting thereof, may be used to represent a given set of videosamples. Additional details related to various ways of performingtransform operations are described in the technical literatureassociated with video encoding including those standards/draft standardsthat have been incorporated by reference as indicated above. The outputfrom the transform processing includes such respective coefficientvalues. This output is provided to a quantizer.

Generally, most image blocks will typically yield coefficients (e.g.,DCT coefficients in an embodiment operating in accordance with discretecosine transform (DCT)) such that the most relevant DCT coefficients areof lower frequencies. Because of this and of the human eyes' relativelypoor sensitivity to high frequency visual effects, a quantizer may beoperable to convert most of the less relevant coefficients to a value ofzero. That is to say, those coefficients whose relative contribution isbelow some predetermined value (e.g., some threshold) may be eliminatedin accordance with the quantization process. A quantizer may also beoperable to convert the significant coefficients into values that can becoded more efficiently than those that result from the transformprocess. For example, the quantization process may operate by dividingeach respective coefficient by an integer value and discarding anyremainder. Such a process, when operating on typical coding units ormacro-blocks, typically yields a relatively low number of non-zerocoefficients which are then delivered to an entropy encoder for losslessencoding and for use in accordance with a feedback path which may selectintra-prediction and/or inter-prediction processing in accordance withvideo encoding.

An entropy encoder operates in accordance with a lossless compressionencoding process. In comparison, the quantization operations aregenerally lossy. The entropy encoding process operates on thecoefficients provided from the quantization process. Those coefficientsmay represent various characteristics (e.g., luma, chroma, residual,etc.). Various types of encoding may be employed by an entropy encoder.For example, context-adaptive binary arithmetic coding (CABAC) and/orcontext-adaptive variable-length coding (CAVLC) may be performed by theentropy encoder. For example, in accordance with at least one part of anentropy coding scheme, the data is converted to a (run, level) pairing(e.g., data 14, 3, 0, 4, 0, 0, −3 would be converted to the respective(run, level) pairs of (0, 14), (0, 3), (1, 4), (2, −3)). In advance, atable may be prepared that assigns variable length codes for valuepairs, such that relatively shorter length codes are assigned torelatively common value pairs, and relatively longer length codes areassigned for relatively less common value pairs.

As the reader will understand, the operations of inverse quantizationand inverse transform correspond to those of quantization and transform,respectively. For example, in an embodiment in which a DCT is employedwithin the transform operations, then an inverse DCT (IDCT) is thatemployed within the inverse transform operations.

An adaptive loop filter (ALF) is implemented to process the output fromthe inverse transform block. Such an adaptive loop filter (ALF) isapplied to the decoded picture before it is stored in a picture buffer(sometimes referred to as a DPB, digital picture buffer). The adaptiveloop filter (ALF) is implemented to reduce coding noise of the decodedpicture, and the filtering thereof may be selectively applied on a sliceby slice basis, respectively, for luminance and chrominance whether ornot the adaptive loop filter (ALF) is applied either at slice level orat block level. Two-dimensional 2-D finite impulse response (FIR)filtering may be used in application of the adaptive loop filter (ALF).The coefficients of the filters may be designed slice by slice at theencoder, and such information is then signaled to the decoder (e.g.,signaled from a transmitter communication device including a videoencoder [alternatively referred to as encoder] to a receivercommunication device including a video decoder [alternatively referredto as decoder]).

One embodiment operates by generating the coefficients in accordancewith Wiener filtering design. In addition, it may be applied on a blockby block based at the encoder whether the filtering is performed andsuch a decision is then signaled to the decoder (e.g., signaled from atransmitter communication device including a video encoder[alternatively referred to as encoder] to a receiver communicationdevice including a video decoder [alternatively referred to as decoder])based on quadtree structure, where the block size is decided accordingto the rate-distortion optimization. It is noted that the implementationof using such 2-D filtering may introduce a degree of complexity inaccordance with both encoding and decoding. For example, by using 2-Dfiltering in accordance and implementation of an adaptive loop filter(ALF), there may be some increasing complexity within encoderimplemented within the transmitter communication device as well aswithin a decoder implemented within a receiver communication device.

In certain optional embodiments, the output from the de-blocking filteris provided to one or more other in-loop filters (e.g., implemented inaccordance with adaptive loop filter (ALF), sample adaptive offset (SAO)filter, and/or any other filter type) implemented to process the outputfrom the inverse transform block. For example, such an ALF is applied tothe decoded picture before it is stored in a picture buffer (again,sometimes alternatively referred to as a DPB, digital picture buffer).Such an ALF is implemented to reduce coding noise of the decodedpicture, and the filtering thereof may be selectively applied on a sliceby slice basis, respectively, for luminance and chrominance whether ornot such an ALF is applied either at slice level or at block level.Two-dimensional 2-D finite impulse response (FIR) filtering may be usedin application of such an ALF. The coefficients of the filters may bedesigned slice by slice at the encoder, and such information is thensignaled to the decoder (e.g., signaled from a transmitter communicationdevice including a video encoder [alternatively referred to as encoder]to a receiver communication device including a video decoder[alternatively referred to as decoder]).

One embodiment is operative to generate the coefficients in accordancewith Wiener filtering design. In addition, it may be applied on a blockby block based at the encoder whether the filtering is performed andsuch a decision is then signaled to the decoder (e.g., signaled from atransmitter communication device including a video encoder[alternatively referred to as encoder] to a receiver communicationdevice including a video decoder [alternatively referred to as decoder])based on quadtree structure, where the block size is decided accordingto the rate-distortion optimization. It is noted that the implementationof using such 2-D filtering may introduce a degree of complexity inaccordance with both encoding and decoding. For example, by using 2-Dfiltering in accordance and implementation of an ALF, there may be someincreasing complexity within encoder implemented within the transmittercommunication device as well as within a decoder implemented within areceiver communication device.

As mentioned with respect to other embodiments, the use of an ALF canprovide any of a number of improvements in accordance with such videoprocessing, including an improvement on the objective quality measure bythe peak to signal noise ratio (PSNR) that comes from performing randomquantization noise removal. In addition, the subjective quality of asubsequently encoded video signal may be achieved from illuminationcompensation, which may be introduced in accordance with performingoffset processing and scaling processing (e.g., in accordance withapplying a gain) in accordance with ALF processing.

With respect to one type of an in-loop filter, the use of an adaptiveloop filter (ALF) can provide any of a number of improvements inaccordance with such video processing, including an improvement on theobjective quality measure by the peak to signal noise ratio (PSNR) thatcomes from performing random quantization noise removal. In addition,the subjective quality of a subsequently encoded video signal may beachieved from illumination compensation, which may be introduced inaccordance with performing offset processing and scaling processing(e.g., in accordance with applying a gain) in accordance with adaptiveloop filter (ALF) processing.

Receiving the signal output from the ALF is a picture buffer,alternatively referred to as a digital picture buffer or a DPB; thepicture buffer is operative to store the current frame (or picture)and/or one or more other frames (or pictures) such as may be used inaccordance with intra-prediction and/or inter-prediction operations asmay be performed in accordance with video encoding. It is noted that inaccordance with intra-prediction, a relatively small amount of storagemay be sufficient, in that, it may not be necessary to store the currentframe (or picture) or any other frame (or picture) within the frame (orpicture) sequence. Such stored information may be employed forperforming motion compensation and/or motion estimation in the case ofperforming inter-prediction in accordance with video encoding.

In one possible embodiment, for motion estimation, a respective set ofluma samples (e.g., 16×16) from a current frame (or picture) arecompared to respective buffered counterparts in other frames (orpictures) within the frame (or picture) sequence (e.g., in accordancewith inter-prediction). In one possible implementation, a closestmatching area is located (e.g., prediction reference) and a vectoroffset (e.g., motion vector) is produced. In a single frame (orpicture), a number of motion vectors may be found and not all willnecessarily point in the same direction. One or more operations asperformed in accordance with motion estimation are operative to generateone or more motion vectors.

Motion compensation is operative to employ one or more motion vectors asmay be generated in accordance with motion estimation. A predictionreference set of samples is identified and delivered for subtractionfrom the original input video signal in an effort hopefully to yield arelatively (e.g., ideally, much) lower energy residual. If suchoperations do not result in a yielded lower energy residual, motioncompensation need not necessarily be performed and the transformoperations may merely operate on the original input video signal insteadof on a residual (e.g., in accordance with an operational mode in whichthe input video signal is provided straight through to the transformoperation, such that neither intra-prediction nor inter-prediction areperformed), or intra-prediction may be utilized and transform operationsperformed on the residual resulting from intra-prediction. Also, if themotion estimation and/or motion compensation operations are successful,the motion vector may also be sent to the entropy encoder along with thecorresponding residual's coefficients for use in undergoing losslessentropy encoding.

The output from the overall video encoding operation is an output bitstream. It is noted that such an output bit stream may of course undergocertain processing in accordance with generating a continuous timesignal which may be transmitted via a communication channel. Forexample, certain embodiments operate within wireless communicationsystems. In such an instance, an output bitstream may undergoappropriate digital to analog conversion, frequency conversion, scaling,filtering, modulation, symbol mapping, and/or any other operationswithin a wireless communication device that operate to generate acontinuous time signal capable of being transmitted via a communicationchannel, etc.

Referring to embodiment 600 of FIG. 6, with respect to this diagramdepicting an alternative embodiment of a video encoder, such a videoencoder carries out prediction, transform, and encoding processes toproduce a compressed output bit stream. Such a video encoder may operatein accordance with and be compliant with one or more video encodingprotocols, standards, and/or recommended practices such as ISO/IEC14496-10—MPEG-4 Part 10, AVC (Advanced Video Coding), alternativelyreferred to as H.264/MPEG-4 Part 10 or AVC (Advanced Video Coding), ITUH.264/MPEG4-AVC.

It is noted that a corresponding video decoder, such as located within adevice at another end of a communication channel, is operative toperform the complementary processes of decoding, inverse transform, andreconstruction to produce a respective decoded video sequence that is(ideally) representative of the input video signal.

In comparing this diagram to the pervious diagram, the signal pathoutput from the inverse quantization and inverse transform (e.g., IDCT)block, which is provided to the intra-prediction block, is also providedto a de-blocking filter. The output from the de-blocking filter isprovided to one or more other in-loop filters (e.g., implemented inaccordance with adaptive loop filter (ALF), sample adaptive offset (SAO)filter, and/or any other filter type) implemented to process the outputfrom the inverse transform block. For example, in one possibleembodiment, a SAO filter is applied to the decoded picture before it isstored in a picture buffer (again, sometimes alternatively referred toas a DPB, digital picture buffer).

With respect to any video encoder architecture implemented to generatean output bitstream, it is noted that such architectures may beimplemented within any of a variety of communication devices. The outputbitstream may undergo additional processing including error correctioncode (ECC), forward error correction (FEC), etc. thereby generating amodified output bitstream having additional redundancy deal therein.Also, as may be understood with respect to such a digital signal, it mayundergo any appropriate processing in accordance with generating acontinuous time signal suitable for or appropriate for transmission viaa communication channel. That is to say, such a video encoderarchitecture may be implemented within a communication device operativeto perform transmission of one or more signals via one or morecommunication channels. Additional processing may be made on an outputbitstream generated by such a video encoder architecture therebygenerating a continuous time signal that may be launched into acommunication channel.

FIG. 7 is a diagram illustrating an embodiment 700 of intra-predictionprocessing. As can be seen with respect to this diagram, a current blockof video data (e.g., often times being square in shape and includinggenerally N×N pixels) undergoes processing to estimate the respectivepixels therein. Previously coded pixels located above and to the left ofthe current block are employed in accordance with such intra-prediction.From certain perspectives, an intra-prediction direction may be viewedas corresponding to a vector extending from a current pixel to areference pixel located above or to the left of the current pixel.Details of intra-prediction as applied to coding in accordance withH.264/AVC are specified within the corresponding standard (e.g.,International Telecommunication Union, ITU-T, TELECOMMUNICATIONSTANDARDIZATION SECTOR OF ITU, H.264 (03/2010), SERIES H: AUDIOVISUALAND MULTIMEDIA SYSTEMS, Infrastructure of audiovisual services—Coding ofmoving video, Advanced video coding for generic audiovisual services,Recommendation ITU-T H.264, also alternatively referred to asInternational Telecomm ISO/IEC 14496-10—MPEG-4 Part 10, AVC (AdvancedVideo Coding), H.264/MPEG-4 Part 10 or AVC (Advanced Video Coding), ITUH.264/MPEG4-AVC, or equivalent) that is incorporated by reference above.

The residual, which is the difference between the current pixel and thereference or prediction pixel, is that which gets encoded. As can beseen with respect to this diagram, intra-prediction operates usingpixels within a common frame (or picture). It is of course noted that agiven pixel may have different respective components associatedtherewith, and there may be different respective sets of samples foreach respective component.

FIG. 8 is a diagram illustrating an embodiment 800 of inter-predictionprocessing. In contradistinction to intra-prediction, inter-predictionis operative to identify a motion vector (e.g., an inter-predictiondirection) based on a current set of pixels within a current frame (orpicture) and one or more sets of reference or prediction pixels locatedwithin one or more other frames (or pictures) within a frame (orpicture) sequence. As can be seen, the motion vector extends from thecurrent frame (or picture) to another frame (or picture) within theframe (or picture) sequence. Inter-prediction may utilize sub-pixelinterpolation, such that a prediction pixel value corresponds to afunction of a plurality of pixels in a reference frame or picture.

A residual may be calculated in accordance with inter-predictionprocessing, though such a residual is different from the residualcalculated in accordance with intra-prediction processing. In accordancewith inter-prediction processing, the residual at each pixel againcorresponds to the difference between a current pixel and a predictedpixel value. However, in accordance with inter-prediction processing,the current pixel and the reference or prediction pixel are not locatedwithin the same frame (or picture). While this diagram showsinter-prediction as being employed with respect to one or more previousframes or pictures, it is also noted that alternative embodiments mayoperate using references corresponding to frames before and/or after acurrent frame. For example, in accordance with appropriate bufferingand/or memory management, a number of frames may be stored. Whenoperating on a given frame, references may be generated from otherframes that precede and/or follow that given frame.

Coupled with the CU, a basic unit may be employed for the predictionpartition mode, namely, the prediction unit, or PU. It is also notedthat the PU is defined only for the last depth CU, and its respectivesize is limited to that of the CU.

FIG. 9 and FIG. 10 are diagrams illustrating various embodiments 900 and1000, respectively, of video decoding architectures.

Generally speaking, such video decoding architectures operate on aninput bitstream. It is of course noted that such an input bitstream maybe generated from a signal that is received by a communication devicefrom a communication channel. Various operations may be performed on acontinuous time signal received from the communication channel,including digital sampling, demodulation, scaling, filtering, etc. suchas may be appropriate in accordance with generating the input bitstream.Moreover, certain embodiments, in which one or more types of errorcorrection code (ECC), forward error correction (FEC), etc. may beimplemented, may perform appropriate decoding in accordance with suchECC, FEC, etc. thereby generating the input bitstream. That is to say,in certain embodiments in which additional redundancy may have been madein accordance with generating a corresponding output bitstream (e.g.,such as may be launched from a transmitter communication device or fromthe transmitter portion of a transceiver communication device),appropriate processing may be performed in accordance with generatingthe input bitstream. Overall, such a video decoding architectures andlamented to process the input bitstream thereby generating an outputvideo signal corresponding to the original input video signal, asclosely as possible and perfectly in an ideal case, for use in beingoutput to one or more video display capable devices.

Referring to the embodiment 900 of FIG. 9, generally speaking, a decodersuch as an entropy decoder (e.g., which may be implemented in accordancewith CABAC, CAVLC, etc.) processes the input bitstream in accordancewith performing the complementary process of encoding as performedwithin a video encoder architecture. The input bitstream may be viewedas being, as closely as possible and perfectly in an ideal case, thecompressed output bitstream generated by a video encoder architecture.Of course, in a real-life application, it is possible that some errorsmay have been incurred in a signal transmitted via one or morecommunication links. The entropy decoder processes the input bitstreamand extracts the appropriate coefficients, such as the DCT coefficients(e.g., such as representing chroma, luma, etc. information) and providessuch coefficients to an inverse quantization and inverse transformblock. In the event that a DCT transform is employed, the inversequantization and inverse transform block may be implemented to performan inverse DCT (IDCT) operation. Subsequently, A/D blocking filter isimplemented to generate the respective frames and/or picturescorresponding to an output video signal. These frames and/or picturesmay be provided into a picture buffer, or a digital picture buffer (DPB)for use in performing other operations including motion compensation.Generally speaking, such motion compensation operations may be viewed ascorresponding to inter-prediction associated with video encoding. Also,intra-prediction may also be performed on the signal output from theinverse quantization and inverse transform block. Analogously as withrespect to video encoding, such a video decoder architecture may beimplemented to perform mode selection between performing it neitherintra-prediction nor inter-prediction, inter-prediction, orintra-prediction in accordance with decoding an input bitstream therebygenerating an output video signal.

Referring to the embodiment 1000 of FIG. 10, in certain optionalembodiments, one or more in-loop filters (e.g., implemented inaccordance with adaptive loop filter (ALF), sample adaptive offset (SAO)filter, and/or any other filter type) such as may be implemented inaccordance with video encoding as employed to generate an outputbitstream, a corresponding one or more in-loop filters may beimplemented within a video decoder architecture. In one embodiment, anappropriate implementation of one or more such in-loop filters is afterthe de-blocking filter.

In accordance with some possible embodiments, a sample adaptive offset(SAO) process may be performed after the completion of the de-blockingfilter process for the decoded picture (e.g., such as in accordance withan SAO filter implemented within the other in loop filter(s) in FIG. 6).This process is performed on a region basis which is defined to be oneor more complete largest coding units (LCUs).

FIG. 11 illustrates an embodiment 1100 of a band offset sample adaptiveoffset (SAO) filtering process. This diagram illustrates the concept ofthe band offset SAO. After each offset is applied, resulting pixels areclipped to the valid 8-bit pixel range [0,255]. In this diagram, offsetsare applied to four consecutive, active bands; the remaining bands arenot modified. Of course, in other embodiments, such offsets may beapplied to non-consecutive bands.

FIG. 12 illustrates an alternative embodiment 1200 of a video encodingarchitecture. In such an embodiment 1200, an any such one or more otherin-loop filters (e.g., implemented in accordance with adaptive loopfilter (ALF), sample adaptive offset (SAO) filter, and/or any otherfilter type) may implemented to process the output from the inversequantization and inverse transform block (e.g., before the de-blockingfilter). In other words, in such embodiments, such one or more otherin-loop filters (e.g., SAO filter on one embodiment) may be appliedbefore de-blocking. In alternative embodiments, such in-loop filters(e.g., implemented in accordance with adaptive loop filter (ALF), sampleadaptive offset (SAO) filter, and/or any other filter type) may beimplemented before de-blocking. However, various aspects, embodiments,and/or their equivalents, of the invention operate to apply such in-loopfilters (e.g., implemented in accordance with adaptive loop filter(ALF), sample adaptive offset (SAO) filter, and/or any other filtertype) before de-blocking as shown in FIG. 12.

In accordance with some embodiments, certain undesirable blockyartifacts may occur when SAO is operative and turned on (e.g., withrespect to embodiments in which such SAO is implemented with respect tothe output from the de-blocking). In those embodiments, this was mainlybecause two neighboring LCUs were using different band offset values. Tomitigate this problem, such SAO may be applied before de-blocking andthe de-blocking may be used to reduce any such undesirable and occurringblocky artifacts in such situations. In this case, the boundary strengthand variable □ and t_(C) used in de-blocking are also decided by the SAOparameters.

From certain perspectives, a band offset SAO may be viewed essentiallyas being a correction filter (e.g., a histogram correction filter insome embodiments). Pixels are classified based on their intensity valueto generate a distribution thereof. For example, with respect to ahistogram embodiment, the pixels (e.g., of one or more largest codingunit (LCU)) are classified based on their intensity value intohistogram-bins or “bands”. The entire pixel range (0-255) is dividedinto 32 uniform bands, and a specific offset is added to all the pixelsin each band. The encoder selects the offset to be applied from therange [−7,7].

While an offset could be applied to all 32 bands, in order to simplifythe band offset process and reduce overhead, a reduced set (e.g., only 4consecutive bands) can actually be modified by band offset SAO in anyLCU. The encoder selects four consecutive bands, for which offsets willbe transmitted. The remaining 28 bands will not be modified (zerooffset). Since there are 32 possible bands, the first band with anon-zero offset is signalled in the bitstream. The band_positionparameter carries this information. The remaining three active bands canbe determined by (band_position+i) % 32 with i ε[1,3]. Note themodulo-operation here, so if the first band is 29, 30, or 31, theremaining bands will wrap around back to 0.

FIG. 13 illustrates various embodiments 1300 of indication (adaptiveand/or explicit signaling) transmitted band offsets in sample adaptiveoffset (SAO) band offset mode. Such operation may be effectuated inaccordance with adaptively indicating the number of transmitted bandoffsets in SAO band offset mode. For example, the number of transmittedband offsets in SAO band offset mode can be LCU size dependent (e.g.,such that the the number of transmitted band offsets in SAO band offsetmode may be a function of LCU size). For example, if the LCU sizedecreases, the number of transmitted bands could also decrease. Asanother example, 4 transmitted band offsets can be used for 64×64 LCUand 3 transmitted band offsets can be used for 32×32 LCU and 2transmitted band offsets can be used for 16×16. Generally, differentrespective numbers of transmitted band offsets in SAO band offset modemay be indicated based upon different respective sizes of LCUs.

The number of transmitted band offsets for each LCU size can also beexplicitly signalled in SPS (sequence parameter set), PPS (pictureparameter size), APS (adaptation parameter set), slice headers, LCUdata, and/or using other portion(s).

FIG. 14 illustrates various embodiments 1400 of indication (adaptiveand/or explicit signaling) band granularity in SAO band offset mode.Such operation may be effectuated in accordance with adaptivelyindicating the granularity in SAO band offset mode.

In certain embodiments, the entire pixel range (0-255) is divided into32 uniform bands. Only 4 bands can actually be modified by band offsetSAO in any LCU. The encoder (e.g., transmitter communication device)selects four consecutive bands, for which offsets will be transmitted.The remaining 28 bands will not be modified (e.g., zero offset). In eachband, a specific offset is added to all the pixels.

Since LCU sizes can be varied (e.g., 64×64, 32×32 or 16×16), thegranularity of bands can be adaptive. For example, the smaller LCU size,the coarser granularity. As another example, if LCU size is 32×32,[0,255] can be uniformly divided into 16 bands and each band covers 16continuous intensity values. Generally, different respectivegranularities of bands in SAO band offset mode may be indicated basedupon different respective sizes of LCUs.

The band granularity for each LCU size can also be explicitly signalledin SPS (sequence parameter set), PPS (picture parameter size), APS(adaptation parameter set), slice headers, LCU data, and/or using otherportion(s).

FIG. 15 illustrates an embodiment 1500 of implicit band index signaling.For example, rather than explicitly signaling band indices, suchinformation can be inferred (e.g., determined based on analysis of theLCU, determined inferentially, etc.) based on the pixel values of thecurrent LCU. For example, by generating a pixel value histogram of anLCU, then band offsets can be applied to the bands in which the numberof pixels is dominant. Such band indices need not necessarily becontinuous (e.g., the band indices may be such that they have adiscontinuous distribution such that at least two successive bandindices may be separated from one another by at least one band indexvalue, in other words, the band indices need not necessarily becontinuous with respect one another).

FIG. 16 illustrates an alternative embodiment 1600 of implicit bandindex signaling. In this very-simplified diagram showing a verysimplified embodiment, there is an LCU with only two gray levels. Thehistogram (e.g., again, just one possible way to depict the distributionof pixels as the reader will understand) tells us 50% pixels have graylevel 25 and 50% pixels have gray level 205. Therefore two band offsetswill be sufficient instead of original four.

FIG. 17 illustrates an embodiment 1700 of band offset coding. In theband offset mode, since sao_band_position indicates the start of theband offset with non-zero offset, the first offset valuesao_offset[cIdx][saoDepth][x0][y0][0] must be non-zero (e.g., in someinstances, the smallest possible value would be a value of 1).Therefore, rather than encoding sao_offset[cIdx][saoDepth][x0][y0][0]directly,

abs(sao_offset[cIdx][saoDepth][x0][y0][0]) □ 1 and the sign bit ofsao_offset[cIdx][saoDepth][x0][y0][0] can be encoded separately, whereabs is a function calculating the absolute value.

FIG. 18 and FIG. 19 illustrate various embodiments of method foroperating one or more devices (e.g., communication devices, receiverand/or decoder devices, transmitter and/or encoder devices, etc.).

Referring to method 1800 of FIG. 18, the method 1800 begins by, via aninput of a communication device, receiving a video signal and aplurality of band offsets from at least one additional communicationdevice, as shown in a block 1810.

The method 1800 continues by analyzing a plurality of pixels associatedwith at least one largest coding unit (LCU) associated with the videosignal to identify a pixel value distribution for use to identify aplurality of band indices, as shown in a block 1820.

The method 1800 then operates by applying the plurality of band offsetsto the plurality of band indices in accordance with filter processing ofthe video signal or a signal based thereon, as shown in a block 1830.

Referring to method 1900 of FIG. 19, the method 1900 begins by, via aninput of the communication device, receiving a video signal and aplurality of band offsets from at least one additional communicationdevice, as shown in a block 1910.

The method 1900 continues by analyzing a plurality of pixels associatedwith at least one largest coding unit (LCU) associated with the videosignal to identify a pixel value distribution for use to identify aplurality of band indices, as shown in a block 1920.

The method 1900 continues by performing sample adaptive offset (SAO)filter processing of the video signal or a signal based thereon togenerate a first filtered signal, such that the SAO filter processingincluding applying the plurality of band offsets to the plurality ofband indices, as shown in a block 1930.

The method 1900 continues by performing de-blocking filter processing ofthe first filtered signal to generate a second filtered signal, as shownin a block 1940.

It is also noted that the various operations and functions as describedwith respect to various methods herein may be performed within any of anumber of types of communication devices, such as using a basebandprocessing module and/or a processing module implemented therein, and/orother components therein. For example, such a baseband processing moduleand/or processing module can generate such signals and perform suchoperations, processes, etc. as described herein as well as performvarious operations and analyses as described herein, or any otheroperations and functions as described herein, etc. or their respectiveequivalents.

In some embodiments, such a baseband processing module and/or aprocessing module (which may be implemented in the same device orseparate devices) can perform such processing, operations, etc. inaccordance with various aspects of the invention, and/or any otheroperations and functions as described herein, etc. or their respectiveequivalents. In some embodiments, such processing is performedcooperatively by a first processing module in a first device, and asecond processing module within a second device. In other embodiments,such processing, operations, etc. are performed wholly by a basebandprocessing module and/or a processing module within one given device. Ineven other embodiments, such processing, operations, etc. are performedusing at least a first processing module and a second processing modulewithin a singular device.

Also, as may be used herein, the terms “substantially” and“approximately” provides an industry-accepted tolerance for itscorresponding term and/or relativity between items. Such anindustry-accepted tolerance ranges from less than one percent to fiftypercent and corresponds to, but is not limited to, component values,integrated circuit process variations, temperature variations, rise andfall times, and/or thermal noise. Such relativity between items rangesfrom a difference of a few percent to magnitude differences. As may alsobe used herein, the term(s) “operably coupled to”, “coupled to”, and/or“coupling” includes direct coupling between items and/or indirectcoupling between items via an intervening item (e.g., an item includes,but is not limited to, a component, an element, a circuit, and/or amodule) where, for indirect coupling, the intervening item does notmodify the information of a signal but may adjust its current level,voltage level, and/or power level. As may further be used herein,inferred coupling (i.e., where one element is coupled to another elementby inference) includes direct and indirect coupling between two items inthe same manner as “coupled to”. As may even further be used herein, theterm “operable to” or “operably coupled to” indicates that an itemincludes one or more of power connections, input(s), output(s), etc., toperform, when activated, one or more its corresponding functions and mayfurther include inferred coupling to one or more other items. As maystill further be used herein, the term “associated with”, includesdirect and/or indirect coupling of separate items and/or one item beingembedded within another item. As may be used herein, the term “comparesfavorably”, indicates that a comparison between two or more items,signals, etc., provides a desired relationship. For example, when thedesired relationship is that signal 1 has a greater magnitude thansignal 2, a favorable comparison may be achieved when the magnitude ofsignal 1 is greater than that of signal 2 or when the magnitude ofsignal 2 is less than that of signal 1.

As may also be used herein, the terms “processing module”, “module”,“processing circuit”, and/or “processing unit” (e.g., including variousmodules and/or circuitries such as may be operative, implemented, and/orfor encoding, for decoding, for baseband processing, etc.) may be asingle processing device or a plurality of processing devices. Such aprocessing device may be a microprocessor, micro-controller, digitalsignal processor, microcomputer, central processing unit, fieldprogrammable gate array, programmable logic device, state machine, logiccircuitry, analog circuitry, digital circuitry, and/or any device thatmanipulates signals (analog and/or digital) based on hard coding of thecircuitry and/or operational instructions. The processing module,module, processing circuit, and/or processing unit may have anassociated memory and/or an integrated memory element, which may be asingle memory device, a plurality of memory devices, and/or embeddedcircuitry of the processing module, module, processing circuit, and/orprocessing unit. Such a memory device may be a read-only memory (ROM),random access memory (RAM), volatile memory, non-volatile memory, staticmemory, dynamic memory, flash memory, cache memory, and/or any devicethat stores digital information. Note that if the processing module,module, processing circuit, and/or processing unit includes more thanone processing device, the processing devices may be centrally located(e.g., directly coupled together via a wired and/or wireless busstructure) or may be distributedly located (e.g., cloud computing viaindirect coupling via a local area network and/or a wide area network).Further note that if the processing module, module, processing circuit,and/or processing unit implements one or more of its functions via astate machine, analog circuitry, digital circuitry, and/or logiccircuitry, the memory and/or memory element storing the correspondingoperational instructions may be embedded within, or external to, thecircuitry comprising the state machine, analog circuitry, digitalcircuitry, and/or logic circuitry. Still further note that, the memoryelement may store, and the processing module, module, processingcircuit, and/or processing unit executes, hard coded and/or operationalinstructions corresponding to at least some of the steps and/orfunctions illustrated in one or more of the Figures. Such a memorydevice or memory element can be included in an article of manufacture.

The present invention has been described above with the aid of methodsteps illustrating the performance of specified functions andrelationships thereof. The boundaries and sequence of these functionalbuilding blocks and method steps have been arbitrarily defined hereinfor convenience of description. Alternate boundaries and sequences canbe defined so long as the specified functions and relationships areappropriately performed. Any such alternate boundaries or sequences arethus within the scope and spirit of the claimed invention. Further, theboundaries of these functional building blocks have been arbitrarilydefined for convenience of description. Alternate boundaries could bedefined as long as the certain significant functions are appropriatelyperformed. Similarly, flow diagram blocks may also have been arbitrarilydefined herein to illustrate certain significant functionality. To theextent used, the flow diagram block boundaries and sequence could havebeen defined otherwise and still perform the certain significantfunctionality. Such alternate definitions of both functional buildingblocks and flow diagram blocks and sequences are thus within the scopeand spirit of the claimed invention. One of average skill in the artwill also recognize that the functional building blocks, and otherillustrative blocks, modules and components herein, can be implementedas illustrated or by discrete components, application specificintegrated circuits, processors executing appropriate software and thelike or any combination thereof.

The present invention may have also been described, at least in part, interms of one or more embodiments. An embodiment of the present inventionis used herein to illustrate the present invention, an aspect thereof, afeature thereof, a concept thereof, and/or an example thereof. Aphysical embodiment of an apparatus, an article of manufacture, amachine, and/or of a process that embodies the present invention mayinclude one or more of the aspects, features, concepts, examples, etc.described with reference to one or more of the embodiments discussedherein. Further, from figure to figure, the embodiments may incorporatethe same or similarly named functions, steps, modules, etc. that may usethe same or different reference numbers and, as such, the functions,steps, modules, etc. may be the same or similar functions, steps,modules, etc. or different ones.

Unless specifically stated to the contra, signals to, from, and/orbetween elements in a figure of any of the figures presented herein maybe analog or digital, continuous time or discrete time, and single-endedor differential. For instance, if a signal path is shown as asingle-ended path, it also represents a differential signal path.Similarly, if a signal path is shown as a differential path, it alsorepresents a single-ended signal path. While one or more particulararchitectures are described herein, other architectures can likewise beimplemented that use one or more data buses not expressly shown, directconnectivity between elements, and/or indirect coupling between otherelements as recognized by one of average skill in the art.

The term “module” is used in the description of the various embodimentsof the present invention. A module includes a functional block that isimplemented via hardware to perform one or module functions such as theprocessing of one or more input signals to produce one or more outputsignals. The hardware that implements the module may itself operate inconjunction software, and/or firmware. As used herein, a module maycontain one or more sub-modules that themselves are modules.

While particular combinations of various functions and features of thepresent invention have been expressly described herein, othercombinations of these features and functions are likewise possible. Thepresent invention is not limited by the particular examples disclosedherein and expressly incorporates these other combinations.

What is claimed is:
 1. A method for video processing, comprising:classifying pixels of a video signal into a plurality of sets of pixelsthat are each associated with a respective largest coding unit (LCU)size within a corresponding band; determining, based on the respectiveLCU size associated with each of the plurality of sets of pixels, aminimum number of band offsets required to filter pixels of the videosignal; and selecting a plurality of band offsets in a discontinuousdistribution based on the respective LCU size associated with each ofthe plurality of sets of pixels and the minimum number of band offsetsrequired to filter the pixels of the video signal.
 2. The method ofclaim 1, wherein the adaptive operations further include transmittingthe plurality of band offsets to a second communication device, thesecond communication device utilizing the plurality of band offsets toapply sample adaptive offset (SAO) filter processing to the videosignal.
 3. The method of claim 1, wherein the adaptive operationsfurther include applying each of the plurality of band offsets to therespective set of pixels of the video signal.
 4. The method of claim 1,wherein a first subset of the plurality of band offsets has a firstgranularity based on a first LCU size associated with a first subset ofa plurality of bands, and wherein a second subset of the plurality ofband offsets has a second, coarser granularity at least based on asecond, smaller LCU size associated with a second subset of theplurality of bands.
 5. The method of claim 1, wherein a first set ofpixels associated with a first band comprises a larger number of pixelsthan a second set of classified pixels associated with a second band. 6.The method of claim 1, wherein a first band index of a plurality of bandindices is associated with a first number of band offsets, and a secondband index of the plurality of band indices is associated with a secondnumber of band offsets.
 7. The method of claim 1, wherein classifyingthe pixels of the video signal is further based on a pixel valuedistribution of the video signal.
 8. The method of claim 1, wherein thediscontinuous distribution is such that at least two of the plurality ofband offsets correspond to respective band indices that arenonconsecutive.
 9. The method of claim 1, wherein each band offset ofthe plurality of band offsets is associated with a respective set ofpixels of the plurality of sets of pixels within a band corresponding toa band index.
 10. The method of claim 1, wherein the video signalcomprises a coding unit or macroblock.
 11. A system for videoprocessing, comprising: one or more processors configured to: classifypixels of a video signal into a plurality of sets of pixels that areeach associated with a respective largest coding unit (LCU) size withina corresponding band; determine, based on the respective LCU sizeassociated with each of the plurality of sets of pixels, a minimumnumber of band offsets required to filter pixels of the video signal;and select a plurality of band offsets in a discontinuous distributionbased on the respective LCU size associated with each of the pluralityof sets of pixels and the minimum number of band offsets required tofilter the pixels of the video signal.
 12. The system of claim 11,wherein the one or more processors are further configured to transmitthe plurality of band offsets to a second system, the second systemutilizing the plurality of band offsets to apply sample adaptive offset(SAO) filter processing to the video signal.
 13. The system of claim 11,wherein the one or more processors are further configured to apply eachof the plurality of band offsets to the respective set of pixels of thevideo signal.
 14. The system of claim 11, wherein a first subset of theplurality of band offsets has a first granularity based on a first LCUsize associated with a first subset of a plurality of bands, and whereina second subset of the plurality of band offsets has a second, coarsergranularity at least based on a second, smaller LCU size associated witha second subset of the plurality of bands.
 15. The system of claim 11,wherein a first set of pixels associated with a first band comprises alarger number of pixels than a second set of classified pixelsassociated with a second band.
 16. The system of claim 11, wherein afirst band index of a plurality of band indices is associated with afirst number of band offsets, and a second band index of the pluralityof band indices is associated with a second number of band offsets. 17.The system of claim 11, wherein classifying the pixels of the videosignal is further based on a pixel value distribution of the videosignal.
 18. The system of claim 11, wherein the discontinuousdistribution is such that at least two of the plurality of band offsetscorrespond to respective band indices that are nonconsecutive.
 19. Thesystem of claim 11, wherein each band offset of the plurality of bandoffsets is associated with a respective set of pixels of the pluralityof sets of pixels within a band corresponding to a band index.
 20. Acircuit for video processing, comprising: a classifier configured toreceive a video signal and classify pixels of the video signal into aplurality of sets of pixels that are each associated with a respectivelargest coding unit (LCU) size within a corresponding band; and a bandselector configured to determine a minimum number of band offsetsrequired to filter pixels of the video signal based on the respectiveLCU size associated with each of the plurality of sets of pixels, andselect a plurality of band offsets in a discontinuous distribution basedon the respective LCU size associated with each of the plurality of setsof pixels and the minimum number of band offsets required to filter thepixels of the video signal.